Differential Regional Immune Response in Chagas Disease

Following infection, lymphocytes expand exponentially and differentiate into effector cells to control infection and coordinate the multiple effector arms of the immune response. Soon after this expansion, the majority of antigen-specific lymphocytes die, thus keeping homeostasis, and a small pool of memory cells develops, providing long-term immunity to subsequent reinfection. The extent of infection and rate of pathogen clearance are thought to determine both the magnitude of cell expansion and the homeostatic contraction to a stable number of memory cells. This straight correlation between the kinetics of T cell response and the dynamics of lymphoid tissue cell numbers is a constant feature in acute infections yielded by pathogens that are cleared during the course of response. However, the regional dynamics of the immune response mounted against pathogens that are able to establish a persistent infection remain poorly understood. Herein we discuss the differential lymphocyte dynamics in distinct central and peripheral lymphoid organs following acute infection by Trypanosoma cruzi, the causative agent of Chagas disease. While the thymus and mesenteric lymph nodes undergo a severe atrophy with massive lymphocyte depletion, the spleen and subcutaneous lymph nodes expand due to T and B cell activation/proliferation. These events are regulated by cytokines, as well as parasite-derived moieties. In this regard, identifying the molecular mechanisms underlying regional lymphocyte dynamics secondary to T. cruzi infection may hopefully contribute to the design of novel immune intervention strategies to control pathology in this infection

Prevalencia de Blastocystis hominis en vendedores ambulantes de comida del municipio Caroní, Estado Bolívar, Venezuela Prevalence of Blastocystis hominis among food handlers from Caroni municipality, Bolivar State, Venezuela

Para determinar la prevalencia de Blastocystis hominis en una muestra de vendedores ambulantes de comida, aparentemente sanos, se realizó un estudio seccional con 415 personas que acudieron al Ambulatorio Urbano tipo III "Manoa" (Municipio Caroní, Estado Bolívar, Venezuela), Programa de Higiene del Adulto, a solicitar el certificado de salud para trabajar como vendedores de comida. Una muestra de heces obtenida por evacuación espontánea fue analizada mediante la técnica de examen directo y método de concentración de Willis. Se encontraron 150 personas parasitadas (36,14%), de ellas 107 (25,78%) con B. hominis. No se observó predilección por el sexo (p > 0,05), pero sí con relación a la edad, siendo las personas de 18 a 27 años las más afectados (ji² = 12,17; g.l. = 4). En el 71,02% de los casos se encontró como parásito único y en 28,98% de los casos asociados a otros parásitos, siendo el más frecuentemente asociado Giardia lamblia (2,41%). En la mayoría de las personas parasitadas (85%) el protozoario se observó en un número menor de cinco células por campo. Se concluye que B. hominis es un parásito frecuente en manipuladores de alimentos del Municipio Caroní, Estado Bolívar, Venezuela.<br>A cross-sectional survey was conducted to determine the prevalence of Blastocystis hominis infection in a random sample of apparently healthy food handlers. A total of 415 individuals attending the Manoa Urban Outpatient Clinic (Caroní Municipality, Bolívar State, Venezuela) in the Adult Hygiene Program and who requested health certification to work as food handlers were studied. Stool samples obtained by spontaneous evacuation were examined by direct microscopy and the Willis concentration method. A total of 150 individuals were infected (36.14%), 107 (25.78%) of whom with B. hominis. There was no difference between males and females (p > 0.05), but there was a significant difference between ages (chi² = 12.17; g.l. = 4), with infection more frequent between 18 and 27 years. In 71.02% of the cases, B. hominis was the only parasite. Giardia lamblia was the parasite most frequently associated with B. hominis (2.41%). In the majority (85%) of infected individuals, less than five microorganisms per microscopic field were observed. We conclude that B. hominis is a frequent intestinal parasite among food handlers in Caroní Municipality, Bolivar State, Venezuela

The grateful dead: damage-associated molecular pattern molecules and reduction/oxidation regulate immunity

The response to pathogens and damage in plants and animals involves a series of carefully orchestrated, highly evolved, molecular mechanisms resulting in pathogen resistance and wound healing. In metazoans, damage- or pathogen-associated molecular pattern molecules (DAMPs, PAMPs) execute precise intracellular tasks and are also able to exert disparate functions when released into the extracellular space. The emergent consequence for both inflammation and wound healing of the abnormal extracellular persistence of these factors may underlie many clinical disorders. DAMPs/PAMPs are recognized by hereditable receptors including the Toll-like receptors, the NOD1-like receptors and retinoic-acid-inducible gene I-like receptors, as well as the receptor for advanced glycation end products. These host molecules 'sense' not only pathogens but also misfolded/glycated proteins or exposed hydrophobic portions of molecules, activating intracellular cascades that lead to an inflammatory response. Equally important are means to not only respond to these molecules but also to eradicate them. We have speculated that their destruction through oxidative mechanisms normally exerted by myeloid cells, such as neutrophils and eosinophils, or their persistence in the setting of pathologic extracellular reducing environments, maintained by exuberant necrotic cell death and/or oxidoreductases, represent important molecular means enabling chronic inflammatory states